(1) Field of the Invention
This invention relates to a method and an apparatus for obtaining, at one time, the optimum duplicative color-separated plates for plural original pictures, in which: the plural original pictures are sequentially scanned and recorded, and the color-separated plates necessary for multicolor printing are made by an image scanning and recording apparatus such as a color scanner; and at that time, appropriate scanning conditions including highlight point, shadow point, gradation correction and color correction data, with which said image scanning and recording apparatus should be set up for every original picture, can be automatically determined.
(2) Description of Prior Art
Heretofore, in an image scanning and recording apparatus such as a color scanner, when plural original pictures different in characteristic with regard to tone, density, gradation and the like from each other are to be duplicatively recorded under peculiar duplicating desired for the pictures, it is a customary practice that the color scanner was set up with said duplicating conditions every time the original pictures are attached to the color scanner, and the original pictures are processed one by one. In the above case, during the period of setting up the duplicating conditions, the color scanner could not be operated its operating ratio being kept low thereby.
In view of the above-described problem, the applicant already proposed a method for enhancing serviceability ratio of a color scanner, in the Japanese laid open Patent Publication (unexamined) Sho. 56-29237, which comprises:
installing a setup-device for setting up a color scanner with duplicating conditions for each original picture (at an offline state, separately from the color scanner); PA0 storing the same duplicating conditions in the memory of the same setup-device; PA0 reading out said duplicating conditions for each original picture from said memory when these original pictures are actually attached to an input cylinder for undergoing scanning and recording; PA0 setting up the color scanner with said duplicating conditions when the original pictures are scanned; PA0 subjecting the plural original pictures parallely to photoelectric scanning by plural scanning means; and PA0 controlling a recording means by means of the image signals obtained from said plural scanning means to let the recording means record duplicate images at desired locations on photosensitive material. PA0 (1) attaching plural original pictures to an original picture inputting cylinder of an image scanning and recording apparatus; PA0 (2) designating the trim-region of each original picture on said cylinder; PA0 (3) performing photoelectric scanning of original pictures prior to image scanning and recording for obtaining image signals from within the trim-region of each original picture; PA0 (4) sampling said image signals at a predetermined sampling pitch; PA0 (5) subjecting said sampled data to statistical classification and treatment for obtaining the density data of the highlight point and the shadow point of each original picture; PA0 (6) determining the scanning condition data necessary for the optimum gradation correction and color correction, on the basis of said density data. PA0 (7) storing said scanning condition data, at every original picture; and PA0 (8) setting up successively the image scanning and recording apparatus with the above-mentioned scanning condition data stored at every scanning of original picture for scanning, recording and obtaining duplicate images.
However, the duplicating conditions for each original picture with which the color scanner is set up by said setup-device are, in most cases, are established for obtaining the images reproduced from the original images with utmost fidelity. Accordingly, an operator should selectively determine appropriate highlight and shadow points out of each colored original because the density range of one original picture usually differs from that of another original picture, then he should set up the color scanner with the density value of each of the said highlight and shadow points, thereby fitting the density range of said colored original to the reproducible range of said color scanner. These are his first tasks to do. And in case color-separated plates are to be prepared by the color scanner, he should also perform gradation correction and color correction to make duplicate prints better than the colored original themselves.
As mentioned above, the operator should determine the setup data for each original picture by means of the setup-device, and should store them in the memory at every original picture. However, it is a troublesome task for even a skilled operator to determine such basic setup data and to set up the color scanner with them skillfully and appropriately.
Thus, the applicant also proposed a method for automatically deciding appropriate scanning conditions for duplicating colored originals irrespective of the degree of an operator's skill, as is disclosed in the Japanese laid open Patent Publication (unexamined) Sho. 56-87044.
According to this method, the aforementioned setup-device is provided with a function of photoelectrically scanning colored originals, and in case appropriate values of highlight and shadow points should be decided, the area of such portions of density range as to be highlight and shadow points are calculated, at first, by the use of three color-separated density signal values D.sub.R, D.sub.G and D.sub.B obtained by photoelectric scanning carried out all over the original picture in the sequential order of scanning. The portions whose areas are greater than the predetermined magnitude are respectively regarded as a highlight point and a shadow point. If such a point (a highlight point or a shadow point) exists plurally on the same original picture, selected is a portion where the three color-separated signals D.sub.R, D.sub.G and D.sub.B are so balanced that they make almost a neutral color altogether. And this selected portion is regarded or discriminated as a highlight point or a shadow point, and the densities of these points are respectively designated as a highlight density D.sub.H and a shadow density D.sub.S. In that case, such a point as a catchlight contained in the trim-region of the original picture should not be mis-selected as a highlight point. For that, the upper limit value of the highlight point which depends on the film material of the original picture should be set up. And if a still higher value is sampled when performing statistical treatment, it should be excluded from the statistical data.
Further, in case of deciding an appropriate characteristic for gradation correction, the distribution density range of the image (the range, D.sub.H to D.sub.S) contained in said original picture and obtained from the foregoing highlight and shadow densities, is divided into n sections by the use of predetermined density boundary D.sub.i, as shown in FIG. 2. Then, the frequency with which the density value included in each section appears is counted, and as a result, a frequency distribution as shown in FIG. 3 is obtained. Based on this frequency distribution, an operator or said setup-device can determine an appropirate gradation correction curve for said original picture.
In the above-mentioned conventional image recording method, and even in an image scanning and recording method in which plural original pictures are subjected to photoelectric scanning in the lump and in which appropriate conditions of adjustable items (such as highlight point, shadow point, gradation correction and color correction) which are to be set at the time of making color-separated plates necessary for multicolor printing can be automatically determined irrespective of the degree of an operator's skill, still there is needed an operator's manual operation of setting up a color scanner with the duplicating conditions which have been automatically determined at every original picture, on a scanner control panel. And alse, there is needed an additional setup-device other than the color scanner apparatus, which raises the cost of the whole apparatus. Therefore, it is currently desired to provide a method and an apparatus by which to solve the above-mentioned problems thereby promoting the automatization and labor-reduction of image scanning and recording operation.